Stoichiometry_StudentNotes2007

# Stoichiometry_StudentNotes2007 - Chemical Stoichiometry...

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Chemical Stoichiometry Stoichiometry - The study of quantities of materials consumed and produced in chemical reactions.

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Atomic Masses Elements occur in nature as mixtures of isotopes Carbon =98.89% 12 C 1.11% 13 C <0.01% 14 C Average atomic mass = (% of each isotope)(atomic mass of each isotope) 100 Carbon atomic mass = 12.01 amu
The Mole The number equal to the number of carbon atoms in exactly 12 grams of pure 12 C. 1 mole of anything = 6.022 × 10 23 units of that thing

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Molar Mass A substance’s molar mass (molecular weight) is the mass in grams of one mole of the compound. CO 2 = 44.01 grams per mole
Percent Composition Mass percent of an element: For iron in iron (III) oxide, (Fe 2 O 3 ) mass mass of element in compound mass of compound % = × 100%

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Formulas molecular formula = (empirical formula) n [ n = integer] molecular formula = C 6 H 6 = (CH) 6 empirical formula = CH
Empirical Formula Determination 1. Base calculation on 100 grams of compound. 2. Determine moles of each element in 100 grams of compound. 3. Divide each value of moles by the smallest of the values. 4. Multiply each number by an integer to obtain all whole numbers.

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Percent Composition/ Empirical Formula Problem 1. An ion containing only oxygen and chlorine is 31% oxygen by mass. What is its empirical formula? 2. What is the percent composition by mass of the elements in the compound NaNO 3 ?
Chemical Equations Chemical change involves a reorganization of the atoms in one or more substances. A representation of a chemical reaction: C 2 H 5 OH + 3O 2 2CO 2 + 3H 2 O reactants products

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Chemical Equation 2 5
Hydrogen and Nitrogen React to Form Ammonia According to the Equation N 2 + 3H 2 2NH 3

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Schematic Diagram of the Combustion Device Used to Analyze Substances for Carbon and Hydrogen
Combustion Stoichiometry Problem A gaseous hydrocarbon sample is completely burned in air, producing 1.80 liters of carbon dioxide at standard

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## This note was uploaded on 05/14/2008 for the course ENERGETICA 203 taught by Professor Tar during the Spring '08 term at ITESM.

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Stoichiometry_StudentNotes2007 - Chemical Stoichiometry...

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